Not Applicable
Not Applicable
This invention was disclosed in the Disclosure Documents Program of the U.S. Patent and Trademark Office on May 4, 1998, Disclosure Document No. 435938.
1. Field of the Invention
This invention relates to medical diagnostic and therapeutic methods and, in particular, to a method for cannulating a retinal blood vessel such that a medication may be injected or a quantity of fluid removed from the blood vessel. Alternatively, a catheter, wire or stent may be placed through the cannula to treat or diagnose an area remote from the insertion site.
2. Description of Related Art
The cannulation of a retinal blood vessel is difficult as the lumen of the blood vessels are less than 200 microns in size. The present day ocular instruments are too large to cannulate the vessel and the dexterity required to maintain the cannula within the blood vessel for several minutes is not commonly available. The piercing of a blood vessel elsewhere in the body to inject medications, perform surgical procedures or remove blood for analysis and treatment is commonly performed. It is therefore, to the effective resolution of the aforementioned problems and shortcomings that the present invention is directed.
Accordingly, it is an object of this invention to provide a microcannula or micropipette whose lumen is small enough to be safely placed within the lumen of a retinal blood vessel and by its configuration is parallel to the lumen when placed through a standard sclerotomy site, as commonly used in vitreoretinal surgery. The terms microcannula and micropipette are used interchangeably throughout the application. To the extent that such terms differ in any way in meaning, if any, then the broadest definition of the two terms is considered to be the definition for both terms for purposes of the instant invention disclosure.
It is another object of this invention to provide, by its configuration and method of attachment, a stable support such that the micropipette may be securely held within the blood vessel so that subsequent maneuvers may be safely accomplished.
It is still another object of this invention to provide a micromanipulator such that the micropipette may be remotely advanced to perforate the retinal blood vessel.
It is yet another object of this invention to provide a portable device that may be easily attached to a standard operating surgical wrist rest and is stable in its xe2x80x9cXxe2x80x9d, xe2x80x9cYxe2x80x9d and xe2x80x9cZxe2x80x9d planes.
It is a further object of this invention to provide a device that, by its configuration and method of attachment, does not inhibit the surgeon""s view when using an operating microscope or otherwise interfere with the use of the operating microscope.
It is yet another object of this invention to provide a safe method such that the surgical procedure may be performed.
The foregoing objects are achieved and the foregoing problems are solved in one illustrative embodiment of the invention in which a retinal blood vessel is cannulated using a micropipette (microcannula) attached to a micromanipulator which is connected to a positioner attached to a standard surgical wrist rest.
More particularly, a sclerotomy is made at the standard distance from the limbus and an illuminated infusion cannula is placed through the sclera at this point. A pars plana vitrectomy may or may not be necessary with further experience. Another sclerotomy is made at the standard distance from the limbus such that the micropipette/microcannula is parallel to the retinal blood vessel chosen to be cannulated. The micropipette is then placed through the sclerotomy overlying the selected retinal blood vessel. The intraocular pressure is lowered to approximately 5 mm of Mercury to allow dilation of the vessel. Once the blood vessel is perforated, it may be advantageous to raise the intraocular pressure to minimize bleeding. The retinal blood vessel may be cannulated manually or the micromanipulator used to advance the micropipette into the retinal blood vessel.
The micropipette tip is preferably at a 135 degree angle to the shaft such that it is parallel to the lumen of the blood vessel when placed through a standard sclerotomy site. The tip of the micropipette is preferably 100 microns in diameter or smaller so it may safely enter the lumen of the retinal blood vessel. The opposite end of the micropipette can be connected to and in fluid communication with a standard surgical tubing and syringe such that fluid may be withdrawn or injected into the retinal vessel. Alternatively, a catheter or wire may be advanced through the microcannula for diagnosing, testing or treatment of an area located at a distance from the insertion site.
In certain situations medication such as Tissue Plasminogen Activator (xe2x80x9cTPAxe2x80x9d) made by Genetech, Inc. and sold under the trademark ACTIVASE can be injected into the retinal vessel. Alternatively, a dye can be injected into the retinal vessel for diagnosing purposes.
The micromanipulator is preferably attached to a positioner that is freely mobile and stable in the xe2x80x9cXxe2x80x9d, xe2x80x9cYxe2x80x9d and xe2x80x9cZxe2x80x9d directions. In the preferred embodiment, the positioner is securely attached to a standard ophthalmic surgery wrist rest by conventional means. The positioner is easy to attach to the wrist rest and may be removed when the device is not needed. At the conclusion of the maneuver, the intraocular pressure is raised ln order to minimize retinal hemorrhaging and the micropipette removed from the blood vessel. The operation is then concluded in standard fashion.